1. Field Of The Invention
This invention relates to arc tubes for high intensity discharge (HID) lamps and especially to apparatus and method of making such arc tubes.
2. Description Of The Prior Art
The arc tubes of high intensity discharge lamps have generally consisted of cylindrical uniform diameter tubes of vitreous quartz or other high temperature glass. Such tubes were prepared by merely cutting long lengths of extruded tubing to the desired length. Electrodes were then sealed in the ends of the arc tube and the arc tube was then exhausted and filled through an exhaust tube attached thereto, which was then tipped off to complete fabrication of the arc tube.